Basics of Cornea and Limbus for Ophthalmology Board Exams

Abstract

The cornea represents a rich pool of multitude of questions for basic ophthalmology exams, as it has several peculiarities regarding its layers, content, dimensions, metabolism, and innervation that distinguish it from other structures. Moreover, the termination of the corneal and transition to the surrounding structure is also an important topic to understand. Pathologies affecting the cornea might be congenital, acquired, or even part of metabolic syndromes. An example of a corneal pathology question is to determine which type of corneal dystrophy may stein with amyloid steins.

This chapter will begin by discussing the main five corneal layers, followed by the content of these layers. Dimensions of the cornea are important, as it is the main refractive structure of the eye, and it is detailed in the next section. After that, corneal innervation is discussed (note that the cornea is an avascular structure), followed by corneal metabolism. The limbus and the transitions occurring at it are then simplified. Finally, corneal pathologies are fully detailed. It is important to note that corneal pathologies are usually contributing only 1–2 questions in basic exams at max, despite being extensive, so one might consider skipping this section if short of time.